In lithography, there is an ongoing desire to reduce the size of features in a lithographic pattern in order to increase the density of features on a given substrate area. In photolithography, the push for smaller features has resulted in the development of technologies such as immersion lithography and extreme ultraviolet (EUV) lithography, which are however rather costly.
A potentially less costly road to smaller features that has gained increasing interest is so-called imprint lithography, which generally involves the use of a “stamp” (often referred to as an imprint template) to transfer a pattern onto a substrate. An advantage of imprint lithography is that the resolution of the features is not limited by, for example, the emission wavelength of a radiation source or the numerical aperture of a projection system. Instead, the resolution is mainly limited to the pattern density on the imprint template.
Imprint lithography involves the patterning of an imprintable medium on a surface of a substrate to be patterned. The patterning may involve pressing together a patterned surface of an imprint template and a layer of imprintable medium such that the imprintable medium flows into recesses in the patterned surface and is pushed aside by protrusions on the patterned surface. The recesses define pattern features of the patterned surface of the imprint template. Typically, the imprintable medium is flowable as the patterned surface and the imprintable medium are pressed together. Following patterning of the imprintable medium, the imprintable medium is suitably brought into a non-flowable or “frozen” state and the patterned surface of the imprint template and the patterned imprintable medium are separated. The substrate and patterned imprintable medium are then typically processed further in order to pattern or further pattern the substrate. The imprintable medium is typically formed from resist droplets on the surface of a substrate to be patterned.
In order to accurately and consistently apply a pattern in the imprintable medium, it is sometimes necessary to move or deform the imprint template. The imprint template may be moved or deformed to take into account or compensate for thermal expansion of the imprint template, or for a magnification error, or for another anomaly. In order to move or deform the imprint template, one or more actuators may be disposed around the imprint template. One or more of these actuators may be activated to push against or pull a portion of the imprint template to establish the desired deformation or change in position of the imprint template.